C-Audio schematic?
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From: Joe Kotroczo on 2 Jul 2008 19:47 On 2/07/08 11:42, in article FdOdnT9R57Xo0PbVRVnyugA(a)bt.com, "Gareth Magennis" <sound.service(a)btconnect.com> wrote: (...) >> >> I've put the pictures here: >> http://homepage.mac.com/kotroczo/PhotoAlbum62.html >> >> Am I right in assuming that the left side should be the same as the right >> side? Same value resistors? It looks like that, but I'd rather be safe >> than >> sorry. > Those 3 power resistors that look burnt are possibly part of the Zobel > network. If you simply replace them they may just go again until you find > why they burnt, which may be RF oscillations. Check also the capacitor(s) > in this network, or better still just replace it as well. And the one on > the other side for good measure. > > The old C Audio RA series used to sometimes suffer from RF problems and > subsequent burnt Zobel networks, I heard it was some kind of poor grounding > design, maybe someone else here could elaborate on causes and/or cures. Thanks for the info. -- Joe Kotroczo kotroczo(a)mac.com
From: Joe Kotroczo on 2 Jul 2008 19:50 On 2/07/08 2:32, in article 486ACCB1.9ACB46A(a)hotmail.com, "Eeyore" <rabbitsfriendsandrelations(a)hotmail.com> wrote: >> I've put the pictures here: >> http://homepage.mac.com/kotroczo/PhotoAlbum62.html >> >> Am I right in assuming that the left side should be the same as the right >> side? Same value resistors? It looks like that, but I'd rather be safe than >> sorry. > > I'd say that's a pretty safe assumption. Odd parts to burn out though, tends > to suggest 'RF' oscillation on that channel perhaps, or RF on the input. > > I see they've changed the internal layout a bit too, replacing the more > durable metal can output devices with plastic encapsulated ones. > > Check for symettrical clipping btw. They EAT output devices by running them > too hot which then fail 'open' so it's not initially obvious. Thanks. -- Joe Kotroczo kotroczo(a)mac.com
From: Phil Allison on 2 Jul 2008 21:18 "Rupert" 'Ultrasonic' would be the correct term. Common mistake just like calling 'infrasonic' "subsonic." No such thing as a subsonic filter, ** Wot idiotic pedantic twaddle. What IS common usage IS correct !!!! The terms " supersonic oscillation " and " subsonic filter " ARE the correct terms cos they are part of audio electronics jargon. ...... Phil
From: Phil Allison on 2 Jul 2008 21:21 <bob(a)yeruncle.com> > > > To be technically correct, RF would apply to any frequency capable of > generating > radio waves, ** WRONG. The context being * audio amps * makes it wrong usage. ....... Phil
From: Phil Allison on 2 Jul 2008 21:33
"Eeysore rabid fuckwit and lying charlatan " > >> Well actually it was to clear up whether "RF" is the correct term for the >> frequencies involved or not. ** The * correct term* is the one in common uses for the matter. > Yes, you can safely ignore Phyllis on this point. ** Very bad advice - from a very arrogant and stupid charlatan. >> I have often heard such oscillations to be termed RF, ** By the terminally ignorant. > Well, most ppl say 'RF' and leave it at that. ** Not where I live nor any audio electronics text I have seen. >> Actually, it really doesn't matter that much, does it. ** The potential for misunderstanding the cause is ENORMOUS if you use the term RF - cause that will get associated with radio mics and or radio / TV broadcast signals being the cause of amplifier smoking. ....... Phil |